Spatiotemporal Dynamics of Mesozooplankton Trophic Structure and Food Web Configuration in the Vicinity of Daya Bay Nuclear Power Plant

Mesozooplankton play a pivotal role in marine pelagic food webs, mediating energy and matter transfer between primary producers and higher trophic levels.. Daya Bay, a semi-enclosed bay in the northern South China Sea, has experienced significant environmental changes due to anthropogenic activities such as thermal discharge from a nuclear power plant and eutrophication..This study investigates the mesozooplankton community structure, feeding preferences, and food web organization through four seasonal cruises (May 2022, February 2023, August 2023, and November 2023) using stable isotope analysis and a Bayesian Isotopic Mixing Model.. Results show that mesozooplankton abundance and diversity are lower in regions affected by thermal discharge, indicating the suppressive effect of elevated temperatures. Seasonal shifts in dominant species were observed, with Penilia avirostris and Dolioletta gegenbauri dominated in spring, and Noctiluca scintillans blooms occurring in summer and winter. Isotopic analysis reveals distinct trophic strategies: copepods display omnivorous habits, while cladocerans and tunicates show stronger herbivorous tendencies. N. scintillans acts as a high-trophic omnivore, preying on copepod larvae and competing for food resources. Overall, the mesozooplankton community features an omnivory-dominated trophic network that enhances resilience but remains sensitive to anthropogenic disturbances. This study clarifies how human-induced environmental changes reshape subtropical coastal trophic pathways, providing a valuable reference for long-term monitoring and ecosystem management in Daya Bay.